Benthos ("Bottom Dwellers") - Those organisms that live in or on the bottom of a body of water. The benthos is one of three divisions of aquatic life; the others are the nekton ("swimmers") and the plankton ("drifters").

Compound leaves - A plant with several leaves or leaflets coming from a common leaf stalk is said to have a compound leaf structure.

Coriolis Effect - The tendency for any moving body on or above the earth's surface, such as a water current, to drift sideways from its course because of the earth's rotation. The Coriolis Effect occurs because the speed of a point on the earth's surface is greater for point near the equator than for a point near the poles. In the Northern Hemisphere the deflection is to the right of the motion. Thus saltwater moving north up the Chesapeake Bay is deflected to the east, and freshwater moving south down the Bay is deflected to the west, resulting in higher salinities on the Eastern Shore of Maryland than on the Western Shore at the same latitude.

Ctenophore - A comb jelly, a transparent gelatinous planktonic animal. Comb jellies have rows of cilia that look like combs. Unlike sea nettles and other jellyfish, comb jellies do not have stinging cells.

Hypotheca - Posterior (rear) part of a dinoflagellate, area below the horizontal flagella.

Indicator species - A species whose status provides information on the overall health of the ecosystem and of other species in that ecosystem. Indicator species reflect the quality and changes in environmental conditions as well as aspects of community composition.

Mesohaline - Moderately brackish water with a salinity range of 5-18 ppt.

Metamorphosis - Developmental changes in the form or structure of an animal.

Molt / Molting - A process where crustaceans and insects shed their exoskeleton (external support). This is an important growth process, enabling the animal's body to expand.

Mucilage - A sticky, gum-like substance produced naturally by some living organisms.

Nekton ("Swimmers") - The nekton includes all aquatic animals that actively swim in the water column, such as fish or squid. The nekton is one of three divisions of aquatic life; the others are the plankton
("drifters") and the benthos ("bottom dwellers").

Parapodia - Fleshy paddle-like appendages on each segment of a polychaete’s body.

Parasite - An organism that lives on or within a body and takes its nourishment from the host without giving any benefit.

Paurometabolous - Paurometabolous insects are very similar to hemimetabolous insects. The only difference is that the wings develop externally on the larvae in paurometabolous insects. Frequently it is difficult to distinguish larvae from adults because both live in the same habitat and feed similarly. Development is gradual and the changes in between molts are subtle and barely noticeable.

Parietal - Referring to the cell wall; in close proximity to the cell wall.

Pectoral fins - Fins attached to the shoulder on the side of the body.

Periostracum - The flaky leathery outer covering on shells that protects from eroding or dissolving.

Phytoplankton - A type of plant plankton, such as algae, that is the basic food source in many aquatic and marine ecosystems.

Plankton ("Drifters") - The plankton includes all aquatic organisms that are carried passively in the water currents. Most are microscopic (such as diatoms, dinoflagellates, and copepods), but others can be relatively large (such as comb jellies and sea nettles). Plankton is one of three divisions of aquatic life; the others are the nekton ("swimmers") and the benthos ("bottom-dwellers").

ppt - An abbreviation for parts per thousand and a measurement of salinity. For example, the open ocean is 35 parts per thousand (ppt). This means that if you had 1,000 buckets of sea water, and could put the salt and water in separate buckets, 35 of the buckets would be filled with nothing but salt.

Protists - Protists are single-celled eucaryotic organisms in the Kingdom Protista, also called the Kingdom Protoctista. The five kingdoms in R.H. Whittaker's taxonomic system are the procaryotes (procaryotic organisms, including the bacteria and cyanobacteria), protists, fungi, plants, and animals. "Animal-like" aquatic protists (such as copepods) are often called protozoans or zooplankton. "Plant-like" aquatic protists (such as diatoms) are commonly called phytoplankton. However, the protist biologist Lynn Margulis points out that "these organisms are no more 'one-celled animals and one-celled plants' than people are shell-less multicellular amebas."

Pycnocline - The pycnocline is the depth in the water column where there is an abrupt change in density, temperature, and salinity. A pycnocline often forms in the Chesapeake Bay and its tidal tributaries when the lighter, warmer, and fresher water coming downstream from the spring rains overlays the denser, colder, and saltier water of the salt wedge bringing water upstream from the ocean.

Rectal chamber - The chamber at the end of the digestive tract; in dragonfly nymphs this chamber contains gills. A dragonfly nymph can move by jet propulsion by shooting water out of its rectal chamber.

Rhizomes - A form of reproduction where a plant grows an underground offshoot from its roots or stem that surfaces and grows into a new plant at a different location.

SAV - Any Submerged Aquatic Vegetation, i.e., vascular aquatic plants that are rooted in the bottom sediments and grow no higher than the surface of the water, such as eelgrass or redhead grass.